E-commerce is far more common in large firms than in small and medium-sized enterprises (SMEs). As a result SMEs risk competitive disadvantages. A growing body of research has attended to this problem but few studies examine the adoption of e-commerce from a broader contextual perspective. To be able to understand SMEs’ adoption of e-commerce it is desirable to study their contextual preconditions, approaches and effects.The purpose of this study is to contribute to the theory building in the e-commerce area by forming a conceptual framework over SMEs’ adoption of e-commerce: the ECA (Electronic Commerce Adoption) framework. A central starting point for the study is Pettigrew’s (1985) contextual framework for strategic changes. The analysis dimensions in Pettigrew’s framework ? content, context and process ? are adapted to adoption of e-commerce. Thus, the ECA framework consists of analysis models that focus on a) the content, b) the context and c) the process of e-commerce adoption in SMEs. Further, the ECA framework includes an analysis model over the interplay between content, context and process and a typology over adoption situations. The SME in its role as a supplier is the unit of analysis. The study uses an abductive approach where results from previous studies in areas such as e-commerce, information systems and decision making are used as sources for forming the ECA framework. The ECA framework is then applied to the collection, interpretation and analyze of empirical data from the case studies of two small and one medium-sized enterprise. The case studies lead to the identification of additional elements that are added to the analysis models.One contribution from the study is the typology over adoption situations. The typology, which builds on studies of Junghagen (1998) and Engsbo et al. (2001), divides the adoption of e-commerce in SMEs into five categories of adoption situations: proactive adoption situations, adaptive adoption situations, pragmatic adoption situations, forced adoption situations and enabled adoption situations. An adoption situation describes what is being adopted (content), why (context) and how (process).Another contribution is the so called adoption guides. These are contextual conditions whose states indicate if a SME will adopt e-commerce or not and if so, which adoption situation they are likely to find themselves in. The adoption guides are: the relative dependence on individual customers, the degree of customer pressure, the strategic needs of e-commerce, the information complexity and, the CEO’s extent of aversion towards risk-taking. Consequently two major conclusions from this study are that SMEs’ e-commerce adoption can be divided into five different adoption situations and a small number of contextual conditions – here called adoption guides – determine which of them a SME tend to go through. The typology enables organizations that educate SMEs or support their development of e-commerce to design their efforts more efficiently and researchers to diversify the studied population. As the study is theory building the contributions and conclusions are propositions that need to be tested empirically in future studies.